Sri Lanka has sent forensic experts to investigate reports of a mass grave of government troops in the north-east.Jailed Tamil Tiger rebels have told the authorities the grave contained the remains of 26 troops they captured and shot dead, officials said.A team of legal and medical officers and a government analyst has been sent to a site bordering Kilinochchi and Mullaitivu districts.Sri Lanka’s long civil war ended in May 2009 with the Tamil Tigers’ defeat.The information we have is that these security personnel were shot dead, cremated and their ashes were buried in a mass grave,” military spokesman Maj Gen Udaya Medawala was quoted as telling the AFP news agency.Both sides have frequently accused each other of war crimes since the end of the conflict.Human rights groups have also accused the two sides of violating human rights, especially in the final months of the war.The Tamil Tigers fought for 25 years for an independent state for Sri Lanka’s ethnic Tamil minority – Bbc